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A stabilized coupled total-Lagrangian and conventional Euler kernel based smoothed particle hydrodynamics (TL-CE SPH) method is presented to model three-dimensional granular flow-structure interaction with rigid and deformable structures. In the coupled TL-CE SPH, the granular material is simulated using CESPH with the Dracker-Prager model, while the structure solver is based on TLSPH. The stabilized TLSPH with corrected kernel gradient, Lagrangian kernel function and hourglass control technique overcomes the common deficiencies of inconsistency, tensile instability and hourglass mode in structure modeling. Based on the Adami boundary condition (Adami et al., 2012), a unified framework for modeling solid boundaries and the granular media-structure interfaces is presented. Furthermore, the advanced GPU-acceleration is employed to achieve high efficiency. The coupled method is employed to simulate problems of granular collapse, granular material-structure interaction at quasi-static regime and granular flows impact on rigid and deformable structures. The presented method can simulate granular flows, the flow-structure interactions, and the deformation and stress of the structures correctly. Furthermore, the GPU-acceleration gives hundreds times of speed-up over serial CPU implementation. The presented method can be applied to large scale three-dimensional cases. [ABSTRACT FROM AUTHOR]

This paper presents a numerical model for simulating free surface flow in porous media with spatially varying porosity. The governing equations are based on the mixture theory. The resistance forces between solid and fluid is assumed to be nonlinear. A multiphase SPH approach is presented to solve the governing equations. In the multiphase SPH, water is modeled as a weakly compressible fluid, and solid phase is discretized by fixed solid particles carrying information of porosity. The model is validated by several numerical examples including seepage through specimen, fast flow through rockfill dam and wave interaction with porous structure. Good agreements between numerical results and experimental data are obtained in terms of flow rate and evolution of free surface. Parameter study shows that (1) the nonlinear resistance law provides more accurate results; (2) particle size and porosity have significant influence on the porous flow. [ABSTRACT FROM AUTHOR]

In this paper, a new Lagrangian differencing dynamics (LDD) method is presented for the simulation of granular flows. LDD is a truly meshless method, which employs second-order consistent spatial operators derived from the Taylor expansion and point renormalization. A decoupled pressure-velocity formulation is employed to derive the pressure Poisson equation, which ensures smooth pressure results in time. Granular media are modeled as viscoplastic materials with the Drucker-Prager yield surface. The velocity equation is formulated and solved in an implicit form, in order to handle large viscosities from the constitutive model. Furthermore, a position-based dynamics technique is used to maintain uniform distribution of the Lagrangian points. The presented LDD method for granular flows is validated by simulating two numerical examples. The results are compared with experimental and numerical data from the literature. [ABSTRACT FROM AUTHOR]

In this work, an advanced hypoplastic model incorporating the critical state is integrated into smoothed particle hydrodynamics (SPH) for numerical investigation of problems with large deformation. This numerical method performs well in cases of element tests such as oedometer test, simple shear test and plain strain compression test, which usually own regular velocity fields. However, the standard SPH implementation will generate significant stress drift away from the failure surface in more complex geotechnical problems featured with dramatically-varying velocity field. This unrealistic stress state may deteriorate the stress state with a further step. As a result, a vicious circle takes place, which could give rise to a calculation failure. With this regard, a return mapping strategy is proposed to regulate the stress state locating beyond the failure surface. To this end, a closed-form solution to predicting the failure surface implicitly incorporated in the hypoplastic model is derived. Finally, the capability of the proposed numerical method is examined with two classical benchmark problems for granular materials, including the sand column collapse and rigid footing by comparing the numerical results with those from experiments and theoretical solutions. [ABSTRACT FROM AUTHOR]

Erosion and deposition induced by overtopping flow strongly impacts the breaching evolution of landslide dams. However, these two processes are not yet sufficiently captured in current dam breaching models. In this paper, we simulate the Erosion and Deposition process during overtopping dam breaching using a novel Smooth Particle Hydrodynamics (ED-SPH) method. A new multi-function boundary is proposed to prevent the penetration of water and soil particles and ensure steady inflows. Dam break and movable erosion scenarios are simulated as a means to validate the model. Dam breach simulations using the ED-SPH method reveal that the proposed model can capture the complex dam soil erosion, entrainment, and depositions behaviors. The soil deposition hinders the eroded particle movement and reduces the water velocity at the water-soil interface. If soil deposition is not considered, as in many existing models, the breaching time decreases and the outburst flood discharge is magnified. We further investigate the re-erosion of deposited soils by varying the re-erosion coefficient. With decreasing the re-erosion coefficient, the peak discharge increases whereas the residual dam height decreases due to the blockage by the deposited soils. [ABSTRACT FROM AUTHOR]

The material point method (MPM) simulation of large-scale landslides can provide useful information to response to landslide hazards in mountainous regions. However, the structured background meshes commonly adopted in MPM fail to accurately capture the complex terrain above which the sliding mass moves. In this work, a novel terrain contact algorithm is proposed and integrated into a GPU-accelerated 3D MPM to model large-scale landslides. The complex terrain is modelled by a fixed triangular surface mesh generated according to the digital elevation model (DEM) and the interaction between the sliding mass and the basal surface is modelled by a contact algorithm between the triangular surface mesh and the material points. Furthermore, a contact detection algorithm based on level-set functions is developed to improve the contact detection efficiency. The detailed computational formulations and numerical implementation based on GPU parallel computing are presented. After the correctness and the efficiency being verified by two numerical examples, the proposed method is applied to simulate the catastrophic Baige landslide that occurred in China in 2018. The results indicate that the present method is both accurate and efficient and can provide a useful tool for numerical study on landslides. [ABSTRACT FROM AUTHOR]

In slope stability analysis, the inherent heterogeneity and spatial variability of soil significantly influence the aftermath of landslides, including critical aspects like runout distance, influence distance, and volume. This research integrates Smoothed Particle Hydrodynamics (SPH) with random field theory to precisely model the large deformation events in slopes with anisotropic shear parameters, while leveraging Graphics Processing Unit (GPU) parallel computing to expedite the generation of random field samples and SPH simulations. This approach meticulously examines how spatial heterogeneity of soil affects slope instability, simulating soil parameters across varied geological settings. It considers the fluctuation scale of anisotropy, the cross-correlation of cohesion and the angle of internal friction, along with their coefficient of variation (CV), to elucidate their impact on landslide magnitude and severity. This study furnishes a robust tool for a holistic assessment of slope impacts and landslide volumes. Additionally, by delineating the computational efficiency disparities between GPUs and Central processing units (CPUs), it underscores the pronounced efficiency benefits of GPU computing. The insights garnered offer fresh perspectives and methodologies in slope stability analysis and disaster risk evaluation, contributing to the finer prediction and management of this prevalent and grave geological hazard. [ABSTRACT FROM AUTHOR]

Particle finite element method (PFEM) is an effective numerical tool for solving large-deformation problems in geomechanics. By incorporating the node integration technique with strain smoothing into the PFEM, we proposed the smoothed particle finite element method (SPFEM). This paper extends the SPFEM to three-dimensional cases and presents a SPFEM executed on graphics processing units (GPUs) to boost the computational efficiency. The detailed parallel computing strategy on GPU is introduced. New computation formulations related to the strain smoothing technique are proposed to save memory space in the GPU parallel computing. Several benchmark problems are solved to validate the proposed approach and to evaluate the GPU acceleration performance. Numerical examples show that with the new formulations not only the memory space can be saved but also the computational efficiency is improved. The computational cost is reduced by ~ 70% for the double-precision GPU parallel computing with the new formulations. Compared with the sequential CPU simulation, the GPU-accelerated simulation results in a significant speedup. The overall speedup ranges from 8.21 to 11.17 for double-precision simulations. Furthermore, the capability of the GPU-accelerated SPFEM in solving large-scale complicated problems is demonstrated by modelling the progressive failure of a long slope with strain-softening soil. [ABSTRACT FROM AUTHOR]